Effect of strain rate and deformation temperature on strain hardening and softening behavior of pure copper

2016 ◽  
Vol 26 (4) ◽  
pp. 1044-1054 ◽  
Author(s):  
Shu-hai HUANG ◽  
Da-yu SHU ◽  
Chuan-kai HU ◽  
Shi-feng ZHU
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Deformation Temperature ◽  
Pure Copper ◽  
Softening Behavior ◽  
Hardening And Softening

scholarly journals A Combined Experimental and Numerical Approach That Eliminates the Non-uniqueness Associated With the Johnson-cook Parameters Obtained Using Inverse Methods

2021 ◽  
Author(s):  
Nishant Ojal ◽  
Harish P. Cherukuri ◽  
Tony L. Schmitz ◽  
Kyle T. Devlugt ◽  
Adam W. Jaycox
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Cutting Forces ◽  
Inverse Method ◽  
Material Model ◽  
Numerical Approach ◽  
Thermal Softening ◽  
Analytical Models ◽  
Initial Yield Stress ◽  
Softening Behavior

Abstract Johnson-Cook constitutive model is a commonly used material model for machining simulations. The model includes five parameters that capture the initial yield stress, strain-hardening, strain-rate hardening, and thermal softening behavior of the material. These parameters are difficult to determine using experiments since the conditions observed during machining (such as high strain-rates of the order of 10 5 /sec - 10 6 /sec) are challenging to recreate in the laboratory. To address this problem, several researchers have recently proposed inverse approaches where a combination of experiments and analytical models are used to predict the Johnson-Cook parameters. The errors between the measured cutting forces, chip thicknesses and temperatures and those predicted by analytical models are minimized and the parameters are determined. In this work, it is shown that only two of the five Johnson-Cook parameters can be determined uniquely using inverse approaches. Two different algorithms, namely, Adaptive Memory Programming for Global Optimization (AMPGO) and Particle Swarm Optimization (PSO), are used for this purpose. The extended Oxley’s model is used as the analytical tool for optimization. For determining a parameter’s value, a large range for each parameter is provided as an input to the algorithms. The algorithms converge to several different sets of values for the five Johnson-Cook parameters when all the five parameters are considered as unknown in the optimization algorithm. All of these sets, however, yield the same chip shape and cutting forces in FEM simulations. Further analyses show that only the strain-rate and thermal softening parameters can be determined uniquely and the three parameters present in the strain-hardening term of the Johnson-Cook model cannot be determined uniquely using the inverse method. A combined experimental and numerical approach is proposed to eliminate this determine all parameters uniquely.

Effect of Deformation Temperature, Strain Rate and Strain on the Strain Hardening Exponent of Copper/Aluminum Laminated Composites

2018 ◽  
Vol 27 (4) ◽  
pp. 096369351802700 ◽  
Author(s):  
Shuaiyang Liu ◽  
Aiqin Wang ◽  
Jingpei Xie
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Deformation Temperature ◽  
Laminated Composites ◽  
Dominant Role ◽  
Strain Hardening Exponent ◽  
Isothermal Compression ◽  
Linear Character ◽  
Dynamic Softening ◽  
Temperature Strain

In order to investigate the strain hardening behaviour of Cu/Al laminated composites, isothermal compression tests were conducted in the temperature range of 300–450 °C and stain rate range of 0.01–1 s−1. Based on the experimental data, stain hardening exponent n was calculated to evaluate the strain hardening ability of Cu/Al laminated composites during the deformation process. The results show that deformation temperature, strain rate, strain and laminated structure are all responsible for the evolution of flow stress during the isothermal compression. The highly non-linear character of Ln σ - Ln ε curves shows the dynamic competition between work hardening and dynamic softening, and dynamic softening gradually plays a dominant role with the increase of strain. Furthermore, strain hardening exponent n is more sensitive to deformation temperature than strain rate. Lower deformation temperature and higher strain rate contribute to the enhancement of strain hardening exponent n.

Compression Deformation Flow Stress Behavior and Prediction of Pure Copper

2016 ◽  
Vol 850 ◽  
pp. 33-40
Author(s):  
Shu Hai Huang ◽  
Shu Xin Chai ◽  
Xiang Sheng Xia ◽  
Da Yu Shu
Keyword(s):  
Flow Stress ◽  
Prediction Model ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Prediction Accuracy ◽  
Prediction Models ◽  
Constitutive Relations ◽  
Pure Copper ◽  
Model Based ◽  
Stress Prediction

The deformation characteristics of pure copper have been investigated by compression tests in the temperature range of 20 °C~900 °C and strain rate range of 0.001 s-1~1 s-1. The results showed that the flow stress of pure copper increased with increasing strain rate and decreasing deformation temperature. Three types of strain-contained flow stress prediction models were developed. The flow stress prediction models based on parameters such as α, Q, lnA and n were related to deformation temperature, strain rate and strain, the prediction accuracy of the flow stress was deeply influenced by the cumulative error of multi-parameter fitting. The flow stress prediction model based on σ, , ε and T constitutive relations and the flow stress prediction model based on GA+BP possessed less correlation with microscopic deformation mechanism, proving to have high prediction accuracy, in which GA+ BP-based flow stress prediction model is in very good agreement with true stress curve, which is of significance to the guidance of hot working of pure copper.

scholarly journals Computational Analysis of Compressive Strain Hardening Exponents of Bimetal with Pearlitic Steel and Low Carbon Steel

2014 ◽  
Vol 553 ◽  
pp. 71-75 ◽  
Author(s):  
Xing Jian Gao ◽  
Zheng Yi Jiang ◽  
Dong Bin Wei ◽  
Si Hai Jiao ◽  
Jing Tao Han
Keyword(s):  
Carbon Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Deformation Temperature ◽  
Computational Analysis ◽  
Compressive Strain ◽  
Low Carbon Steel ◽  
Pearlitic Steel ◽  
Low Carbon ◽  
Wide Range

The compressive strain hardening behaviour of a novel bimetal with pearlitic steel and low carbon steel was investigated by computational analysis based on the isothermal compression tests in a wide range of deformation temperature and strain rate. The Hollomon’s equation was employed to calculate the strain hardening exponent (SHE) with the assistance of mathematical manipulation. The result shows that the logarithmic relationship between the flow stress and plastic strain of the bimetal is highly non-linear, which results in the variation of the SHE of the bimetal. This variation reflects the dynamic competition between the strain hardening and softening mechanism by the varying value of the SHE in the range of 0.4 to-0.4. Furthermore, the influences of deformation temperature and strain rate on the SHE are significant. With decreasing temperature and increasing strain rate, the strain hardening of the bimetal was enhanced, while the dynamic recrystallisation was activated under the opposite conditions with the evidence of negative SHE value.

scholarly journals Understanding the Strain Path Effect on the Deformed Microstructure of Single Crystal Pure Aluminum

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1189
Author(s):  
Yingjue Xiong ◽  
Qinmeng Luan ◽  
Kailun Zheng ◽  
Wei Wang ◽  
Jun Jiang
Keyword(s):  
Strain Rate ◽  
Single Crystal ◽  
Strain Path ◽  
Mechanical Response ◽  
Pure Aluminum ◽  
Lattice Rotation ◽  
Softening Behavior ◽  
Theoretical Support ◽  
Commercial Applications ◽  
Electron Back Scattered Diffraction

During plastic deformation, the change of structural states is known to be complicated and indeterminate, even in single crystals. This contributes to some enduring problems like the prediction of deformed texture and the commercial applications of such material. In this work, plane strain compression (PSC) tests were designed and implemented on single crystal pure aluminum to reveal the deformation mechanism. PSC tests were performed at different strain rates under strain control in either one-directional or two-directional compression. The deformed microstructures were analyzed according to the flow curve and the electron back-scattered diffraction (EBSD) mappings. The effects of grain orientation, strain rate, and strain path on the deformation and mechanical response were analyzed. Experimental results revealed that the degree of lattice rotation of one-dimensional compression mildly dependents on cube orientation, but it is profoundly sensitive to the strain rate. For two-dimensional compression, the softening behavior is found to be more pronounced in the case that provides greater dislocations gliding freeness in the first loading. Results presented in this work give new insights into aluminum deformation, which provides theoretical support for forming and manufacturing of aluminum.

scholarly journals Fully Atomistic Molecular Dynamics Computation of Physico-Mechanical Properties of PB, PS, and SBS

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1088 ◽  
Author(s):  
Yang Kang ◽  
Dunhong Zhou ◽  
Qiang Wu ◽  
Fuyan Duan ◽  
Rufang Yao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Strain Rate ◽  
Strain Hardening ◽  
Md Simulation ◽  
Md Simulations ◽  
Strain Rates ◽  
Young’S Moduli ◽  
Plastic Modulus ◽  
Styrene Butadiene ◽  
Butadiene Styrene

The physical properties—including density, glass transition temperature (Tg), and tensile properties—of polybutadiene (PB), polystyrene (PS) and poly (styrene-butadiene-styrene: SBS) block copolymer were predicted by using atomistic molecular dynamics (MD) simulation. At 100 K, for PB and SBS under uniaxial tension with strain rate ε ˙ = 1010 s−1 and 109 s−1, their stress–strain curves had four features, i.e., elastic, yield, softening, and strain hardening. At 300 K, the tensile curves of the three polymers with strain rates between 108 s−1 and 1010 s−1 exhibited strain hardening following elastic regime. The values of Young’s moduli of the copolymers were independent of strain rate. The plastic modulus of PS was independent of strain rate, but the Young’s moduli of PB and SBS depended on strain rate under the same conditions. After extrapolating the Young’s moduli of PB and SBS at strain rates of 0.01–1 s−1 by the linearized Eyring-like model, the predicted results by MD simulations were in accordance well with experimental results, which demonstrate that MD results are feasible for design of new materials.

Sign in / Sign up

Export Citation Format

Share Document